The short answer
Five of the six vitamin B12 supplements we compared contain 1,000 µg per capsule, 400 times the reference intake. This dose is not excessive: the gut absorbs only a small fraction of it. Above all, it allows spaced-out dosing: two capsules a week are enough for maintenance, which brings the annual cost down to 13.80 EUR at Dieti Natura. The same use costs 39.90 EUR at Nat&Form, nearly three times as much for an equivalent composition.
The ranking
| Brand and size | Form | Price | Price per capsule | One year at 1 capsule a day | One year of maintenance, 2,000 µg a week |
|---|---|---|---|---|---|
| Dieti Natura, 90 capsules of 1,000 µg | methylcobalamin, with B6 and B9 | 11.95 EUR | 0.133 EUR | 48.50 EUR | 13.80 EUR |
| Dynveo, 60 capsules of 250 µg | methyl-, hydroxo- and adenosylcobalamin | 8.90 EUR | 0.148 EUR | 54.10 EUR | not applicable: daily dose |
| Nutri&Co, 120 capsules of 1,000 µg | methylcobalamin MecobalActive | 19.90 EUR | 0.166 EUR | 60.50 EUR | 17.25 EUR |
| Novoma, 120 capsules of 1,000 µg | methylcobalamin | 19.90 EUR | 0.166 EUR | 60.50 EUR | 17.25 EUR |
| Nat&Form, 30 capsules of 1,000 µg | methylcobalamin | 11.50 EUR | 0.383 EUR | 139.90 EUR | 39.90 EUR |
| Sensilab, 30 capsules of 1,000 µg | methylcobalamin, with methylfolate (400 µg) | 19.99 EUR | 0.666 EUR | 243.20 EUR | 69.30 EUR |
Why 1,000 µg when the requirement is 4 µg
Anses, the French food safety agency, sets the adequate intake at 4 µg a day for an adult. A 1,000 µg capsule therefore seems absurd, and this is the most common objection. It rests on a mistake: B12 is not absorbed like other vitamins.
It goes through two routes. The first, active, uses a protein in the stomach, intrinsic factor, which captures only about 1.5 to 2 µg per meal: beyond that, it becomes saturated. The second, passive, lets through about 1% of the dose, whatever the amount swallowed. A 1,000 µg capsule therefore delivers in the order of 10 µg absorbed, or two to three days of requirement. That is what makes twice-weekly dosing possible.
B12 has no safe upper limit set by EFSA, as no adverse effect has been identified at supplement doses; the excess is eliminated in urine.
Methylcobalamin or a combined form: it matters little
Five products out of six use methylcobalamin, presented as the « active » form. Dynveo combines three forms: methyl-, hydroxo- and adenosylcobalamin. All are converted by the body into the two forms it uses. For an adult with no particular condition, the form is not a decisive criterion; taking it regularly is.
Dieti Natura adds vitamin B6 and B9, at low doses (210 µg and 30 µg). This does no harm, but it is not a selling point: these two vitamins are rarely lacking in a varied diet. Sensilab combines 400 µg of folate as methylfolate (200% of the reference value): a plus if you also want folate, but it comes at a price, as this is the most expensive product in the table.
Who really needs it
Everyone who is vegan, without exception. B12 does not exist in usable form in plants; seaweed and unfortified yeast are not reliable sources. For vegetarians, eggs and dairy products provide some, but often not enough. People over 60 absorb dietary B12 less well, and certain treatments reduce its absorption, including metformin and proton pump inhibitors: in these cases, a blood test prescribed by a doctor settles the question.
For omnivores, diet almost always suffices. Our ranking of foods rich in vitamin B12 shows this, and our guide to B12 supplementation details the signs of deficiency.
Our sources
- Official Dieti Natura, Dynveo, Nutri&Co and Nat&Form pages, accessed on 24/09/2026, and official Novoma page, accessed on 27/10/2026: doses, forms, sizes, prices and ingredient lists.
- Official Sensilab page, accessed on 27/10/2026: dose, form, size, price and ingredient list.
- Anses, opinion of 21 February 2025 on nutritional references: adequate intake of 4 µg of vitamin B12 a day for adults.
- Regulation (EU) No 1169/2011, Annex XIII: reference intake of 2.5 µg.
- EFSA, opinion on reference values for cobalamin (2015): active and passive absorption mechanisms, no upper limit.